Resource efficient or sustainable buildings?

Written by Karl Downey on 19 May 2015.

In mid 2014, the European Commission published a Communication which focused on resource efficiency opportunities in the building sector (COM 2014/0445). Initially, this communications was due to focus on “sustainable buildings”. Unfortunately, this was not the case as not only was the title of the final modified, but also the focus of the content which stood squarely in the environmental segment of sustainability. Society and economy appeared, regrettably, to have fallen by the wayside.

This notwithstanding, the Communication goes broadly in the right direction, and indicates an intention from the Commission to work intensely on this subject over the next few years. This work will be led jointly by DG ENV and DG GROW. One hopes that other DGs, such as DG Energy, can also be closely involved given the relevance to, for example, the Energy Performance of Buildings Directive (Directive 2010/31/EU), which would ensure a balance across all aspects of sustainability.

One idea presented in the Communication is the framework for environmental assessment of buildings. There is no doubt that such an EU-wide framework could prove useful. Currently, numerous commercial “green rating schemes” for buildings are in use across Europe, the biggest of these being LEED, BREEAM, HQE and DGNB. None of these has a large market presence outside of its country of origin – hence the “EU framework” idea. Certainly, a convergence of these schemes across Europe could enhance the single market for construction materials and services. For construction product manufacturers, it is vital to have a harmonised system for providing data to feed any kind of building assessment.

Luckily, a harmonised assessment system already exists! This is the suite of standards developed by the CEN (European Committee for Standardisation) technical committee TC 350 “Sustainability of construction works”. Not only that, the CEN/TC 350 standards are more powerful and scientifically rigorous than the commercial schemes, since they are wholly based on life-cycle analysis (LCA). To top it off, the system provides standards for all three pillars of sustainability, from the construction product level up to the level of the works, allowing one to perform a complete LCA of a building, over its whole life, making them the perfect tool for the building sector. The very fact that data at product level can be “summed up” to give the result for the whole building allows one to ensure that decisions taken at product level really lead to better outcomes in terms of sustainability at the building level – something which is not as obvious as it seems. Take the example of concrete’s thermal mass, a unique property which contributes to a building’s energy performance. When the air is warm, concrete absorbs unwanted heat and lowers room temperatures. When temperatures fall in the evening, concrete releases this heat. This heat storage effect results in more comfortable internal room temperatures during the day in summer and a more stable temperature year round. The property of thermal mass is inherent to the concrete, but it is only at the level of the concrete envelope’s interaction with the rest of the building during the use phase that the benefit can be observed.

CEN/TC 350 standards provide for assessment over a range of parameters: global warming, ozone depletion, resource depletion, renewable energy use and so on. The Commission’s Communication, on the other hand, signals an intention to limit the framework to a small number of “core indicators”. The difficulty with this is deciding which ones to focus on. Picking too few indicators could mean that efforts to improve performance on these indicators results in a worsening of performance for other impacts. A full range of indicators is needed to allow full assessment to take place at the building level.

The second main area covered by the Communication is construction and demolition (C&D) waste, or rather, creating a market for reuse of this waste. Creating markets is the right aspect to look at, since whether or not these materials are used is primarily down to whether there is a market for them. Fortunately for concrete, recycling is not technically difficult and it can be 100% recycled after demolition. Recycled aggregates from concrete are traditionally used in unbound applications such as for road base, and they can also be used as aggregates for new concrete. But the question is which of these applications should we recycle C&D waste? There are those who repeat “closed-loop” recycling (recycling back into the same application) as a mantra – it is seen as the Holy Grail of recycling. But open-loop recycling, i.e. reuse in another application, has environmental benefits too. For concrete, since virgin aggregates need to be extracted anyway to fulfill the total demand, it should be carefully considered whether the best use of recycled aggregates is in new concrete or in unbound applications. Likewise, an intention, signaled in the Communication, to set benchmarks on recycled content would have to be undertaken with care. Given the variable supply of materials coming from C&D, one would not wish to see a situation whereby recycled aggregates travel long distances (translating into an increase in transport-related CO2 emissions), even when virgin aggregates are available nearby. The converse is also true: in some cases, such as in large cities, recycled material will have the advantage of being available closer to where it is needed. All this to say that recycling is worthwhile when the environmental and economic benefits are clear, which is not always the case. Which brings us back to building assessment: a whole-life approach, taking all impacts into account, ensures that the right decision is taken – or rewarded – in each case.

As to where all this will lead, only time will tell. To guide the work of developing the framework for assessment of buildings, and the indicators to be used, a study let by DGs ENV and GROW will be undertaken by JRC, with stakeholder involvement . The Concrete Initiative is involved in this process and will give input every step of the way.

A version of this blog was originally published as part of a series of stakeholder views on the World Green Building Council website.